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March 10, 1964 I .1. F. STEPHENS 3,124,212

ACOUSTICAL INSULATION AND METHOD OF MAKING SAME Filed March 5, 1959 v 2 Sheets-Sheet 1 INV EN TOR.

(Mg W 14 TTORNEK Jase 0h E 5720/74/75" March 10, 1964 J. F. STEPHENS 3,124,212

ACOUSTICAL INSULATION AND METHOD OF MAKING SAME Filed March 5, 1959 2 Sheets-Sheet 2 INVENTOR.

1 Joseph E fife Mans JAM! ,4 TmQNEK United States Patent 3,124,212 ACOUSTICAL INSULATION AND METHOD OF MAKING SAME Joseph F. Stephens, Kansas City, Mo., assignor to Gustin- Bacon Manufacturing Company, Kansas City, M0,, a corporation of Delaware I Filed Mar. 5, 1959, Ser. No. 797,492 5 Claims. (Cl. 18133) This invention relates to acoustical insulation paneling and refers more particularly to an acoustical panel which is tough but highly flexible, has a washable and decorative permanent exposed face, is resilient and light in weight, and which is capable of absorbing sounds through a wide range of frequencies, and to the method of making same.

This application is a continuation-in-part of my copendpending application SerialNo. 355,850, filed May 18, 1953, now abandoned.

Heretofore many different types of structural materials have been developed which, through a combination of various factors, have been accorded relatively good sound absorbing properties. Perhaps the most commonly accepted and used material is the familiar compressed fiber wallboard which is generally produced in rectangular panels provided with a pattern of perforations which tend to eliminate reflection of the sound waves.

Othertypes rely instead upon the use of a thin and inflexible covering sheet adhered to the paneling material along the edges to provide what may be termed an open drumhead construction in which the lack of adhesion of the cover sheet to the panel except at the edges permits free and unrestricted vibration of the sheet and reduces sound reflectivity. In this particular type of construction it has been the general practice to apply the facing to relatively rigid board-like sheets of'material having a high density. In some instances the backing material has alsobeen perforated, but the basic reliance for obtaining good acoustical properties has been on the relatively loose thin facing applied thereto.

Other types of sound insulation all derived from and varying little in their basic construction from the foregoing general .classifications have been proposed in the past, but all have one primary disadvantage in common, and that is that they are inflexible and in manycases even brittle. To applyvthese materials to irregular or curved surfaces has in the past presented problems which are extremely difficult of solution, and which result in costly assembly procedures and a great deal of wastage of material.

For example, in the use of material of the fiber wallboard type, which is relatively inflexible and also brittle, the application of panels to curved wall surfaces or columns or the like necessitates cutting into strips of relatively narrow width which are thus conformed as nearly as possible to the contour of the background surface. As a result a great number of joints are necessary which not only creates a difliculty in attaching the material to the wall base, but also leaves much to be desired in appearance. These problems are also inherent in the use of faced materials of the type referred to earlier herein, but an additional difllculty with the latter resides in the lack of adhesion of the facing sheet to the panel except at the edges. It will be evident that to cut this material intermediate its edges results in leaving one edge of the facing free (the edge along the line of severance) and thus destroying the acoustical value of the material.

Moreover, there are other disadvantages in previously known insulation panels which appear both during assembly and thereafter. It is Well recognized that in both the unfaced and faced materials heretofore known the application to the exposed. surface of the material of a coat of 3,124,212 Patented Mar. 10, 1964 treme flexibility, low density and high resiliency, and in' which the main body is provided with a tough integral rubber-like facing which, in combination with the resiliency of the base material, results in a unitary panel structure having optimum noise reduction characteristics combined with great durability, complete washability, and ease in handling. A further object of the invention is to provide an acoustical panel of the character described which can be cut from its raw sheet form into panels of any desired configuration without the loss of the sound absorbing properties, and furthermorewhich can be installed with a minimum of cost and effort. In this connection it is another object to provide an acousticalpanel having formed in the surface thereof designs and patterns of varigated shape without destroying the continuity of the surface nor altering in any Way, except possibly improving its functional advantages from an acoustical standpoint. Acoustical panels embodying my invention can be produced in a wide variety of colors and fabric-like patterns which are not susceptible of being eradicated by washing or cleaning.

till another object of the invention is to provide an acoustical panel in which the danger of breakage or accidental crushing is virtually non-existent. Panels con structed according to this invention have a high degree of resistance to permanent distortion which might otherwise occur in other materials as the result of impacts or other compressive forces, and are also capable of withstanding puncturing through accidental contact with pointed or sharp objects. These advantages accrue mainly as a result of the inherent resilience of the main body of the panel coupled with the flexibility and toughness of the integral facing which is applied and uniquely keyed thereto.

Yet another object of the invention is to provide an acoustical insulation panel which not only incorporates excellent acoustical properties, but which is also flame resistant and has good heat insulating properties. Panels according to my invention are ideally suited for use in drop ceilings, the panel having sufficient inherent resistance to flexural deflection when edge suspended in a horizontal plane as to present and maintain a flat ceiling surface.

Still another object of the invention is to provide a retired for manufacturing insulation panels of the character described which is inexpensive to perform, safe and simple to put in practice.

Other and further objects of the invention together with the features of novelty appurtenant thereto will appear in the course of the following description.

In the accompanying drawings which form a part of the specification and are to be read in conjunction therewith, and in which like reference numerals indicate like parts in the various views: 7 I

FIG. 1 is a perspective partially schematic view showing certain components of apparatus which can be employed in connection with the invention;

FIG. 2 represents a vertical section on a reduced scale through the apparatus of FIG. 1 with the addition of a platen and the material worked on and illustrates certain steps in the process of manufacture;

FIG. 3 is an enlarged fragmentary section illustrating generally the character of the final product;

FIGURE 4 shows an acoustical insulation panel provided with a facing having a pattern or design in relief; and

FIGURE shows an alternative embodiment of an acoustical insulation panel.

Briefly described, my invention encompasses an insulation panel (and a method of producing same) which in essence consists of a resilient or springy low density bonded glass fiber main body having formed integral therewith a flexible, tough, rubber-like facing completely covering the exposed side of the main body. I have shown in FIG. 3 a fragmentary section of a panel constructed according to the invention. Reference numeral 1% indicates the main body, while 11 indicates the flexible facing.

The character and composition of the fibrous main body of the panel is critical in obtaining the desired acoustical and structural properties for the panel. The main body should be composed of glass fibers having an average diameter of microns or less, preferably about 4 microns, and the fibers should be distributed in random orientation within the mat. Above the average of 10 microns, insufiicient resilience is obtained. While a completely heterogeneous, three dimensional orientation is not necessary, there nevertheless should be a substantial portion of fibers extending transversely between the major faces of the mat. Air deposition of the fibers on a suction conveyor, a practice already known to the art, produces a fiber orientation of the type I desire for the product. As a bonding agent a heat reactive material is used, and this may be one of a variety of compositions, including, but not necessarily limited to, phenol condensation products. In order to obtain bonding points limited mainly to the points of intersection of the fibers within the mat, the preferable range of percentage of binder is approximately 11% to by weight of the mat, or 13% to based on the weight of the glass fibers. Within these resin and fiber diameter ranges, and at the densities hereinafter set forth, the mat will be honeycombed with interstitial air spaces which are necessary to provide the resiliency contributing to the high acoustical efiiciency of the panel. Following the curing the main body of the mat should lie in a density range of between 2 and 5 lbs. per cubic foot with 3 lbs. per cubic foot being the optimum for panels inch in thickness and 2 x 4 in lateral dimensions. At the density and thickness set forth, panels constructed according to the invention require no central support to prevent deflection when the panels are installed in the usual drop ceiling, that is, with the panel supported only at the edges in horizontal planes.

The facing 11 applied to the main body is in its starting form a liquid, viscous material of cream-like consistency which is thermoplastic in character and which, when applied to one face of the main body and subjected to pressure and heat, produces a tough flexible film which is securely bonded and keyed to the mat. Preferably the film material comprises a vinyl chloride polymer coupled with suitable plasticizers and stabilizers. Materials of this type are known generally as plastisols or organisols, depending on the compositions used, and have the property of being easily spreadable and flowable in liquid form, yet capable of being fused by heat and pressure to produce a tough elastic rubber-like composition which is moisture and air proof. A typical plastisol formulation suitable for use in the invention is as follows:

Grams Vinyl chloride-vinyl acetate copolymer (in discrete particles) 2610 Dioctyl phthalate 1140 Tricresyl phosphate 800 Light stabilizer 86.4 Heat stabilizer 43 Titanium dioxide 100 Pigment 227 The facing materials are applied to and merged with the main body while still in liquid form. To accomplish this the liquid plastisol is first spread uniformly over a nonpermeabie surface such as the surface of the caul plate 12 illustrated in FIGS. 1 and 2.

Preferably plate 12 is formed of metal, for example, stainless steel. The plate is removably set on a box 13 having raised edges 14 which form a frame around the caul plate. The bottom side of the box against which the caul plate bears is capable of heating the caul plate and for this purpose there may be employed a grid of steam pipes 15. It will be understood, however, that electric resistance heating elements or any other appropriate means for heating it to the desired temperature may be employed.

After applying the liquid plastisol to the caul plate a layer or mat of glass fibers having the characteristics previously described is set down on top of the plastisol, as indicated at it) in FIG. 2. The glass fiber body may at this time be either in the uncured state, that is, in a state where the resin binder is incorporated in the mat, but yet unfused, or in the cured state. For the purposes of the present example we will consider that it is in the uncured state.

Following application of the fibrous body upon the still liquid plastisol a pressure platen 16 of like dimensions with the caul plate is placed upon the exposed surface of the mat within the box. The pressure platen is weighted or otherwise subjected to pressure to insure that the mat will be compressed. Stops 17 are interposed between it and the caul plate to control the thickness to which the fibrous material will be compressed and the extent to which the liquid plastisol will be driven or forced into the interstices of that face of the fibrous body with which it is in contact.

The position of the stops 17 relative the surface of the caul plate, that is, the distance between them, is dependent upon the status of the fibrous body at the time the process is being carried out. If the fibrous body is still in the uncured state, then the stops 17 will be spaced above the caul plate a distance equal to the final thickness which is desired for the panel. If, however, the fibrous mat has already been cured prior to application to the liquid plastisol, then the stops will be only slightly lower than the top surface of the mat when the latter is in position in the box. In the latter case, only a slight amount of pressure is required to cause the liquid plastisol to penetrate enough into the mat to cause it to surround adjacent fibers to firmly key it thereto.

In a case of starting with the uncured fibrous structure, I have found that by maintaining a temperature in the box at 300350 F. for a period of 20 minutes while the mat is under compression results in setting of the mat to the thickness and density desired, and also insures of drying or fusing of the plastisol into a tough rubber-like facing which is adhered securely to the mat. The quantity of plastisol used determines the final thickness of the coating, which, for best results, should not exceed an average of 35 mils. Following the curing or setting period the plate is cooled and the insulation material is stripped therefrom, its outer or faced surface is molded by the smooth caul plate into a flat, continuous facing which presents an even, attractive appearance.

In the case of employing an already cured fibrous material as the starting material for the main body, the temperature in the box will still be raised to 300-350" F., but it need be maintained at this temperature only for a period necessary to result in fusing or drying of the plastisol.

It will be understood, of course, that the pressure exerted to compress the fibrous body and plastisol together should be limited to a value which will produce only partial embedding of the plastisol into the adjoining fibrous structure. This pressure is, however, necessary. I have found that it is not possible to obtain satisfactory results by simply spreading a coating of the type here involved on the surface of the mat and relying upon gravity to cause the necessary penetration.

It will be evident that by providing an etched or relieved surface on the caul plate, 21 facing can be provided with designs or patterns in relief if desired, as illustrated at 11 in FIG. 4. i

I also propose providing in the facing a submerged pattern of strands and threads by scattering various colored textile fibers, for example, rayon, glass and the like, over the surface of the liquid plastisol after the latter has been applied to the caul plate, but before imposition of the fibrous body. I have observed that as the fibrous body is pressed into the plastisol these strands are displaced toward the outer face of the plastisol and become visible therein following stripping of the completed article from the apparatus. A typical product of the foregoing type is illustrated in FIG. 5, the facing being shown at 11" and the strands at 20.

A further modification of the invention is to provide the facing with a foam-like construction. This can be accomplished simply by incorporating in the liquid plastic a blowing or foaming agent, for example, ammonium carbonate. The subsequent application of heat to the plastisol during formation of the panel results in release of gases which tend to expand and form bubbles in the facing.

The low density of the main body coupled with the high resiliency and dimensional stability resulting from its composition, as earlier described, cooperate with the flexible yet relatively dense and tough plastic facing to create very favorable acoustical properties. The plastic serves as the bonding agent securing the facing to the mat and inasmuch as it is rubber-like in character, there is inherent resiliency in the facing itself and in the portions thereof which adhere to, surround and strike into the fibrous structure of the mat. The relatively dense plastic coating is quite effective in the acoustical absorption in the lower frequency ranges, say 200 to 250 c.p.s., and the resiliency of the mat makes possible absorption of frequencies in higher ranges and up to, but in decreasing effectiveness, approximately 2000 c.p.s. The spectrum of sound frequencies in most spaces where acoustical materials are employed, for example, ofiices, auditoria, etc., is predom inantly .below 1000 c.p.s. and hence a panel having a panel having a tough elastic facing according to the invention, and which is backed up by a resilient mat material of the character set forth herein, performs very effectively in these locations.

Moreover, the characteristics last mentioned also insure of a panel which can be subject to rough usage Without danger of crushing or breaking. The panels can be produced in any size consistent with practicality of use and they can be cut to any shape without danger of separating or breaking the connection between the facing and the fibrous body. The glass and resin composition produces a flame-proof construction which makes the panels highly suitable for drop ceilings overlaid by an open space.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim:

1. A composite acoustical insulation panel comprising a porous resilient and springy mat-like glass fiber main body honeycombed with interstitial air spaces, the fibers having an average diameter of no greater than 10 microns and being disposed in random orientation with a substantial portion extending transverse to the planes of the opposed faces of the main body and bonded together at their intersections with a heat reactive hinder, the density of the main body being between approximately 2 and 5 pounds per cubic foot, and a thin lamination of flexible rubber-like material applied to at least one face of the main body, the outermost fibers of said one face being firmly embedded in that side of said lamination confronting said one face and portions of the lamination distributed into some of the interstitial air spaces closely adjacent said one face with other portions bridging others of said spaces, the exposed side of the lamination presenting an imperforate continuous surface.

2. A composite acoustical insulation panel as in claim 1 wherein said lamination includes as embedded therein adjacent its exposed side visible textile strands,

3. A composite acoustical insulation panel as in claim 1 wherein said rubber-like lamination is a fused plastisol.

4. A composite acoustical insulation panel as in claim 1 wherein said rubber-like lamination isa foamed and fused plastisol.

5. A method of manufacturing acoustical insulation;

panels from fibrous mat comprising the steps of applying to a plate-like surface a thin film of liquid plastisol, scattering over the top of said film a plurality of individual fibers, setting down on top of said film and fibers a resilient and springy fibrous mat, compressing said mat, fibers and film together with only enough pressure to cause said film to partially distribute itself into the adjaccnt surface of the mat and to force said fibers toward that side of the film in contact with said plate whereby to dispose the fibers closely adjacent said side, and heating said compressed mat and film while under compression to cure said film and cause it to adhere to the face of said mat and confine said fibers in the film.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A COMPOSITE ACOUSITICAL INSULATION PANEL COMPRISING A POROUS RESILIENT AND SPRINGY MAT-LIKE GLASS FIBER MAIN BODY HONEYCOMBED WITH INTERSTITIAL AIR SPACES, THE FIBERS HAVING AN AVERAGE DIAMETER OF NO GREATER THAN 10 MICORNS AND BEING DIPOSED IN RANDOM ORIENTATION WITH A SUBSTANTIAL PORTION EXTENDING TRANSVERSE TO THE PLANES OF THE OPPOSED FACES OF THE MAIN BODY AND BONDED TOGETHER AT THEIR INTERSECTIONS WITH A HEAT REACTIVE BINDER, THE DENSITY OF THE MAIN BODY BEING BETWEEN APPROXIMATELY 2 AND 5 POUNDS PER CUBIC FOOT, AND A THIN LAMINATION OF FLEXIBLE RUBBER-LIKE MATERIAL APPLIED TO AT LEAST ONE FACE OF THE MAIN BODY, THE OUTERMOST FIBERS OF SAID ONE FACE BEING FIRMLY EMBEDDED IN THAT SIDE OF SAID LAMINATION CONFRONTING SAID ONE FACE AND PORTIONS OF THE LAMINATION DISTRIBUTED INTO SOME OF THE INTERSTITIAL AIR SPACES CLOSELY ADJACENT SAID ONE FACE WITH OTHER PORTIONS BRIDGING OTHERS OF SAID SPACES, THE EXPOSED SIDE OF THE LAMINATION PRESENTING AN IMPERFORATE CONTINUOUS SURFACE.
 5. A METHOD OF MANUFACTURING ACOUSTICAL INSULATION PANELS FROM FIBROUS MAT COMPRISING THE STEPS OF APPLYING TO A PLATE-LIKE SURFACE A THIN FILM OF PLURALITY OF INDIVIDUAL FIBERS, SETTLING DOWN ON TOP OF SAID FILM AND FIBERS A RESILIENT AND SPRINGLY FIBROUS MAT, COMPRESSING SAID MAT, FIBERS AND FILM TOGETHER WITH ONLY ENOUGH PRESSURE TO CAUSE SAID FILM TO PARTIALLY DISTRIBUTE ITSELF INTO THE ADJACENT SURFACE OF THE MAT AND TO FORCE SAID FIBERS TOWARD THAT SIDE OF THE FILM IN CONTACT WITH SAID PLATE WHEREBY TO DISPOSE THE FIBERS CLOSELY ADJACENT SAID SIDE, AND HEATING SAID COMPRESSED MAT AND FILM WHILE UNDER COMPRESSION TO CURE SAID FILM AND CAUSE IT TO ADHERE TO THE FACE OF SAID MAT AND CONFINE SIDE FIBERS IN THE FILM 